With improved instrumentation and scanning techniques, breast ultrasound screening is earning a prominent role in the detection of breast cancer in women with dense breasts when no lump is felt and no abnormalities are detected on the mammogram.
Results of a study by Barbara Weinstein, md, of Pittsburgh, Pennsylvania, and colleagues, led to the recommendation that complete bilateral breast ultrasound be done in women with dense breasts whenever a cancer is suspected. This recommendation applies particularly to cases in which breast-conservation surgery (lumpectomy) is being contemplated. The finding of an additional cancer site may indicate that more extensive surgery is necessary. The serendipitous finding in this study of nine breast cancers in women who had no suspicious mammographic finding suggests that the role of ultrasound in the detection of breast cancer in women with dense breasts needs to be investigated further.
According to Dr. Weinstein, "While it may not prove to be cost effective to screen all women with mammographically dense breasts by sonography, our study suggests that it should be considered as an adjunct to mammography for women with dense breasts who have a strong family history or personal history of breast cancer."
The authors' findings support breast ultrasound's value. In 20 women, breast cancer was found by sonography only. That is, no lump was felt in the area where the cancer was discovered, and no abnormal changes were present on the mammogram in this location. The women ranged in age from 34 to 83 years, with a median age of 52. The occult cancers ranged in size from 5 to 24 mm, with a median size of 9 mm. Of interest was the fact that 10 of the 20 women were at high risk for breast cancer: They had a mother or sister with breast cancer, or a personal history of breast cancer.
Nine of the cancers were discovered when a suspicious abnormality at a different location in the same breast was being evaluated. In two other instances, a second breast cancer was found in the opposite breast. Seven cancers were detected as an incidental finding in the same breast while unrelated benign abnormalities were being scanned. Two of the malignancies were detected in breasts scanned because of the marked degree of breast density found on the mammogram.
Expanded Use of Ultrasound
Although many imaging specialists advocate "targeted" breast ultrasound examinations (scanning only the area of breast that is in question), the authors of the study routinely surveyed the entire breast when the mammogram was limited by marked breast density. If there were any suspicious findings, both breasts were carefully scrutinized. All suspicious abnormalities were then further evaluated by means of fine-needle aspiration biopsy, core biopsy, and/or surgical excision. To date, the major indications for breast ultrasound include evaluation of suspected mammographic abnormalities, evaluation of palpable breast masses, and evaluation of symptomatic women who are under age 30, pregnant, or lactating. It is hoped that this study will expand the use of ultrasound, especially in cases in which the mammogram is limited by marked breast density.
Dr. Weinstein reported the study's findings on March 18 at the American Institute of Ultrasound in Medicine's 40th Annual Convention in New York.